Pulling-up-type continuous casting apparatus and pulling-up-type continuous casting method

ABSTRACT

A pulling-up-type continuous casting apparatus according to an aspect of the present invention includes a holding furnace that holds molten metal, a shape defining member configured to define a cross-sectional shape of a cast-metal article to be cast by a molten-metal passage section through which the molten metal passes, and a nozzle that blows a cooling gas on the cast-metal article, the cast-metal article being formed as the molten metal that has passed through the molten-metal passage section. The shape defining member includes cooling means for cooling the molten metal on an outlet side of the molten-metal passage section, and temperature-maintaining means for maintaining a temperature of the molten metal on an inlet side of the molten-metal passage section. An end face shape of the molten-metal passage section is curved to conform to a surface shape of the molten metal pulled up from the molten-metal surface.

TECHNICAL FIELD

The present invention relates to a pulling-up-type continuous casting apparatus and a pulling-up-type continuous casting method.

BACKGROUND ART

As a revolutionary continuous casting method that does not requires any mold, Patent Literature 1 proposes a pulling-up-type free casting method. As shown in Patent Literature 1, after a starter is submerged under the surface of a melted metal (molten metal) (i.e., molten-metal surface), the starter is pulled up, so that some of the molten metal follows the starter and is drawn up by the starter by the surface film of the molten metal and/or the surface tension. Note that it is possible to continuously cast a cast-metal article having a desired cross-sectional shape by drawing the molten metal and cooling the drawn molten metal through a shape defining member disposed in the vicinity of the molten-metal surface.

In the ordinary continuous casting method, the shape of the cast-metal article in the longitudinal direction as well as the shape thereof in cross section is defined by the mold. In the continuous casting method, in particular, since the solidified metal (i.e., cast-metal article) needs to pass through the inside of the mold, the cast-metal article has such a shape that it extends in a straight-line shape in the longitudinal direction.

In contrast to this, the shape defining member used in the free casting method defines only the cross-sectional shape of the cast-metal article, while it does not define the shape in the longitudinal direction. Further, since the shape defining member can be moved in the direction parallel to the molten-metal surface (i.e., in the horizontal direction), cast-metal articles having various shapes in the longitudinal direction can be produced. For example, Patent Literature 1 discloses a hollow cast-metal article (i.e., a pipe) having a zigzag shape or a helical shape in the longitudinal direction rather than the straight-line shape.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2012-61518

SUMMARY OF INVENTION Technical Problem

The present inventors have found the following problem.

In the free casting method disclosed in Patent Literature 1, the molten metal drawn up through the shape defining member is cooled by a cooling gas. Specifically, a cooling gas is blown on the cast metal immediately after it is solidified and the molten metal is thereby indirectly cooled. It should be noted that by increasing the flow rate of the cooling gas, the casting speed can be increased and the productively can be thereby improved. However, there has been a problem that when the flow rate of the cooling gas is increased, an undulation occurs in the molten metal drawn up from the shape defining member due to the cooling gas and hence the size accuracy and the surface quality of the cast-metal article deteriorate.

The present invention has been made in view of the above-described problem, and an object thereof is to provide a pulling-up-type continuous casting apparatus and a pulling-up-type continuous casting method capable of producing cast-metal articles having excellent size accuracy and surface quality, and having excellent productivity.

Solution to Problem

A pulling-up-type continuous casting apparatus according to an aspect of the present invention includes:

a holding furnace that holds molten metal;

a shape defining member disposed near a molten-metal surface of the molten metal held in the holding furnace, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast by a molten-metal passage section through which the molten metal passes; and

a nozzle that blows a cooling gas on the cast-metal article, the cast-metal article being formed as the molten metal that has passed through the molten-metal passage section solidifies, in which

the shape defining member includes:

-   -   cooling means for cooling the molten metal on an outlet side of         the molten-metal passage section; and     -   temperature-maintaining means for maintaining a temperature of         the molten metal on an inlet side of the molten-metal passage         section, and

an end face shape of the molten-metal passage section is curved to conform to a surface shape of the molten metal pulled up from the molten-metal surface.

The above-described configuration makes it possible to provide a pulling-up-type continuous casting apparatus capable of producing cast-metal articles having excellent size accuracy and surface quality, and having excellent productivity.

The temperature-maintaining means preferably includes a heat-insulating film formed on an undersurface of the shape defining means and/or a heater formed on the inlet side of the molten-metal passage section.

A pulling-up-type continuous casting apparatus according to another aspect of the present invention includes:

a holding furnace that holds molten metal;

a shape defining member disposed near a molten-metal surface of the molten metal held in the holding furnace, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast as the molten metal passes through the shape defining member; and

a nozzle that blows a cooling gas on the cast-metal article, the cast-metal article being formed as the molten metal that has passed through the shape defining member solidifies, in which

the shape defining member includes:

-   -   a lower-part shape defining member in contact with the molten         metal held in the holding furnace; and     -   an upper-part shape defining member disposed above the         lower-part shape-memory member, the upper-part shape defining         member including cooling means for cooling the molten metal that         passes through the upper-part shape defining member.

The above-described configuration makes it possible to provide a pulling-up-type continuous casting apparatus capable of producing cast-metal articles having excellent size accuracy and surface quality, and having excellent productivity.

The cooling means is preferably a channel through which a refrigerant flows. Further, the refrigerant is preferably a gas for the sake of safety. Further, the refrigerant is preferably the same gas as the cooling gas, so that the equipment can be simplified.

A pulling-up-type continuous casting method according to an aspect of the present invention includes:

a step of pulling up molten metal held in a holding furnace while making the molten metal pass through a molten-metal passage section of a shape defining member, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast; and

a step of blowing a cooling gas on the cast-metal article, the cast-metal article being formed from the molten metal that has passed through the molten-metal passage section, in which

the shape defining member includes:

-   -   cooling means for cooling the molten metal on an outlet side of         the molten-metal passage section; and     -   temperature-maintaining means for maintaining a temperature of         the molten metal on an inlet side of the molten-metal passage         section, and

an end face shape of the molten-metal passage section is curved to conform to a surface shape of the molten metal pulled up from the molten-metal surface.

The above-described configuration makes it possible to provide a pulling-up-type continuous casting method capable of producing cast-metal articles having excellent size accuracy and surface quality, and having excellent productivity.

A heat-insulating film formed on an undersurface of the shape defining means and/or a heater formed on the inlet side of the molten-metal passage section are preferably used as the temperature-maintaining means.

A pulling-up-type continuous casting method according to another aspect of the present invention includes:

a step of pulling up molten metal held in a holding furnace while making the molten metal pass through a shape defining member, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast; and

a step of blowing a cooling gas on the cast-metal article, the cast-metal article being formed from the molten metal that has passed through the shape defining member, in which

the shape defining member includes:

-   -   a lower-part shape defining member in contact with the molten         metal held in the holding furnace; and     -   an upper-part shape defining member disposed above the         lower-part shape-memory member, and

the upper-part shape defining member includes cooling means for cooling the molten metal that passes through the upper-part shape defining member.

The above-described configuration makes it possible to provide a pulling-up-type continuous casting method capable of producing cast-metal articles having excellent size accuracy and surface quality, and having excellent productivity.

A channel through which a refrigerant flows is preferably used as the cooling means. Further, a gas is preferably used as the refrigerant for the sake of safety. Further, the same gas as the cooling gas is preferably used as the refrigerant, so that the equipment can be simplified.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a pulling-up-type continuous casting apparatus and a pulling-up-type continuous casting method capable of producing cast-metal articles having excellent size accuracy and surface quality, and having excellent productivity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross section of a free casting apparatus according to a first exemplary embodiment;

FIG. 2 is a plan view of a shape defining member 102 according to the first exemplary embodiment;

FIG. 3 is a schematic cross section of a free casting apparatus according to a comparative example to the first exemplary embodiment;

FIG. 4 is a plan view of a shape defining member 102 according to a modified example of the first exemplary embodiment;

FIG. 5 is a side view of the shape defining member 102 according to the modified example of the first exemplary embodiment;

FIG. 6 is a schematic cross section of a free casting apparatus according to a second exemplary embodiment; and

FIG. 7 is a schematic cross section of a free casting apparatus according to a third exemplary embodiment.

DESCRIPTION OF EMBODIMENTS

Specific exemplary embodiments to which the present invention is applied are explained hereinafter in detail with reference to the drawings. However, the present invention is not limited to exemplary embodiments shown below. Further, the following descriptions and the drawings are simplified as appropriate for clarifying the explanation.

First Exemplary Embodiment

Firstly, a free casting apparatus (pulling-up-type continuous casting apparatus) according to a first exemplary embodiment is explained with reference to FIG. 1. FIG. 1 is a schematic cross section of a free casting apparatus according to the first exemplary embodiment. As shown in FIG. 1, the free casting apparatus according to the first exemplary embodiment includes a molten-metal holding furnace 101, a shape defining member 102, a support rod 104, an actuator 105, a cooling gas nozzle(s) 106, and a pulling-up machine 108. In FIG. 1, the xy-plane forms a horizontal plane and the z-axis direction is the vertical direction. More specifically, the positive direction on the z-axis is the vertically upward direction.

The molten-metal holding furnace 101 contains molten metal M1 such as aluminum or its alloy, and maintains the molten metal M1 at a predetermined temperature. In the example shown in FIG. 1, since the molten-metal holding furnace 101 is not replenished with molten metal during the casting process, the surface of molten metal M1 (i.e., molten-metal surface) is lowered as the casting process advances. Alternatively, the molten-metal holding furnace 101 may be replenished with molten metal as required during the casting process so that the molten-metal surface is kept at a fixed level. Note that the position of the solidification interface can be raised by increasing the setting temperature of the holding furnace and the position of the solidification interface can be lowered by lowering the setting temperature of the holding furnace. Needless to say, the molten metal M1 may be a metal or an alloy other than aluminum.

The shape defining member 102 is made of stainless steel, for example, and disposed near the molten-metal surface. In the example shown in FIG. 1, the shape defining member 102 is disposed so that its underside principal surface (undersurface) is in contact with the molten-metal surface. The shape defining member 102 can define the cross-sectional shape of cast metal M3 to be cast while preventing oxide films formed on the surface of the molten metal M1 and foreign substances floating on the surface of the molten metal M1 from entering the cast metal M3. The cast metal M3 shown in FIG. 1 is a solid cast-metal article having a plate-like shape in a horizontal cross section (hereinafter referred to as “lateral cross section”).

FIG. 2 is a plane view of the shape defining member 102 according to the first exemplary embodiment. Note that the cross section of the shape defining member 102 shown in FIG. 1 corresponds to a cross section taken along the line I-I in FIG. 2. As shown in FIG. 2, the shape defining member 102 has, for example, a rectangular shape as viewed from the top, and has a rectangular opening (molten-metal passage section 103) having a thickness t1 and a width w1 at the center thereof. The molten metal passes through the rectangular opening (molten-metal passage section 103). Further, the xyz-coordinate system shown in FIG. 2 corresponds to that shown in FIG. 1.

As shown in FIG. 1, the molten metal M1 follows the cast metal M3 and is pulled up by the cast metal M3 by its surface film and/or the surface tension. Further, the molten metal M1 passes through the molten-metal passage section 103 of the shape defining member 102. That is, as the molten metal M1 passes through the molten-metal passage section 103 of the shape defining member 102, an external force(s) is applied from the shape defining member 102 to the molten metal M1 and the cross-sectional shape of the cast metal M3 is thereby defined. Note that the molten metal that follows the cast metal M3 and is pulled up from the molten-metal surface by the surface film of the molten metal and/or the surface tension is called “held molten metal M2”. Further, the boundary between the cast metal M3 and the held molten metal M2 is the solidification interface SIF.

Here, FIG. 3 is a schematic cross section of a free casting apparatus according to a comparative example to the first exemplary embodiment. As seen from a comparison between FIGS. 1 and 3, the shape defining member 102 according to the first exemplary embodiment is thicker than the shape defining member 2 according to the comparative example, and covers roughly the entire surface of the held molten metal M2. Therefore, the shape defining member 102 can prevent (or reduce) an undulation on the surface of the held molten metal M2, which would otherwise be caused by a cooling gas blown from the cooling gas nozzle 106 onto the cast metal M3. As a result, the size accuracy and the surface quality of the cast-metal article can be improved.

Further, it is possible to increase the casting speed and improve the productivity compared to the related art by increasing the flow rate of the cooling gas. It should be noted that the closer the position of the solidification interface SIF is to the shape defining member 102, the more above effects increase. However, the flexibility in the shape in the longitudinal direction of the cast metal M3 decreases, thus leading to the cast metal M3 extending on a straight line.

Further, in the shape defining member 2 according to the comparative example, the size of the opening (inlet) on the lower side of the molten-metal passage section 3 is equal to that of the opening (outlet) on the upper side thereof, and the end face of the molten-metal passage section 3 is flat and perpendicular to the principal surface of the molten-metal passage section 3. In contrast to this, in the shape defining member 102 according to the first exemplary embodiment, the inlet of the molten-metal passage section 103 is a size larger than the outlet thereof, and the end face of the molten-metal passage section 103 is oblique to the principal surface thereof. Further, the end face of the molten-metal passage section 103 is curved in a convex shape to conform to the surface shape of the held molten metal M2 pulled up from the molten-metal surface.

Note that structures/components other than the shape defining member 2 of the free casting apparatus according to the comparative example are similar to those of the free casting apparatus according to the first exemplary embodiment, and therefore their explanations are omitted.

The shape defining member 102 includes cooling means disposed in the internal upper part thereof. Specifically, the shape defining member 102 includes, as the cooling means, a refrigerant channel(s) 2 a near the upper side (outlet side) of the molten-metal passage section 103. Therefore, the shape defining member 102 can effectively cool the held molten metal M2 that is located near the outlet of the molten-metal passage section 103 and is passing through the shape defining member 102, and thereby maintain the position of the solidification interface SIF in the vicinity of the shape defining member 102.

The refrigerant channel 2 a is formed, for example, in a ring shape so as to surround the molten-metal passage section 103. For the sake of safety, it is preferable that a cooling gas similar to the cooling gas blown from the cooling gas nozzle 106 onto the cast metal M3 be used as the refrigerant flowing through the refrigerant channel 2 a. Further, the same gas as the cooling gas blown from the cooling gas nozzle 106 is preferably used as the cooling gas flowing through the refrigerant channel 2 a, so that the equipment can be simplified.

Further, the shape defining member 102 includes temperature-maintaining means on the underside thereof in order to prevent (or reduce) a decrease in the temperature of the molten metal M1 caused by the shape defining member 102. When the temperature of the molten metal M1, which has not yet passed through the shape defining member 102, is lowered, undesirable solidified pieces are formed in the molten metal M1 and they have harmful effects on the size accuracy and the surface quality of the cast-metal article. Therefore, the shape defining member 102 includes, as the temperature-maintaining means, a heat-insulating film 2 b composed of a mold wash having a heat-insulating property applied to the undersurface thereof.

Examples of the mold wash include a vermiculite mold wash. The vermiculite mold wash is a mold wash that is obtained by suspending refractory fine particles made of silicon oxide (SiO₂), iron oxide (Fe₂O₃), aluminum oxide (Al₂O₃), or the like in water.

The heat-insulating film 2 b can maintain the temperature of the molten metal M1 that is located near the inlet of the molten-metal passage section 103 and is going to pass through the shape defining member 102. Therefore, it is possible to prevent (or reduce) a decrease in the temperature of the molten metal M1 and improve the size accuracy and the surface quality of the cast-metal article.

The support rod 104 supports the shape defining member 102.

The support rod 104 is connected to the actuator 105. By the actuator 105, the shape defining member 102 can be moved in the up/down direction (vertical direction) and the horizontal direction through the support rod 104. With this configuration, for example, it is possible to move the shape defining member 102 downward as the molten-metal surface is lowered due to the advance of the casting process. Further, since the shape defining member 102 can be moved in the horizontal direction, the shape in the longitudinal direction of the cast metal M3 can be changed.

The cooling gas nozzle (cooling unit) 106 is cooling means for blowing a cooling gas (such as air, nitrogen, and argon) supplied from the cooling gas supply unit (not shown) on the cast metal M3 and thereby cooling the cast metal M3. The position of the solidification interface can be lowered by increasing the flow rate of the cooling gas and the position of the solidification interface can be raised by reducing the flow rate of the cooling gas. Note that although it is not shown in the figure, the cooling gas nozzle (cooling unit) 106 can also be moved in the horizontal direction and the vertical direction in accordance with the movement of the shape defining member 102.

By cooling the cast metal M3 by the cooling gas while pulling up the cast metal M3 by using the pulling-up machine 108 connected to the starter ST, the held molten metal M2 located in the vicinity of the solidification interface SIF is successively solidified, and the cast metal M3 is thereby formed. The position of the solidification interface can be raised by increasing the pulling-up speed of the puffing-up machine 108 and the position of the solidification interface can be lowered by reducing the pulling-up speed.

Next, a free casting method according to the first exemplary embodiment is explained with reference to FIG. 1.

Firstly, a starter ST is lowered and made to pass through the molten-metal passage section 103 of the shape defining member 102, and the tip of the starter ST is submerged into the molten metal M1.

Next, the starter ST starts to be pulled up at a predetermined speed. Note that even when the starter ST is pulled away from the molten-metal surface, the molten metal M1 follows the starter ST and is pulled up from the molten-metal surface by the surface film and/or the surface tension. That is, the held molten metal M2 is formed. As shown in FIG. 1, the held molten metal M2 is formed in the molten-metal passage section 103 of the shape defining member 102. That is, the held molten metal M2 is shaped into a given shape by the shape defining member 102.

Next, since the starter ST is cooled by the cooling gas blown from the cooling gas nozzle 106, the held molten metal M2 successively solidifies from its upper side toward its lower side. As a result, the cast metal M3 grows. In this manner, it is possible to continuously cast the cast metal M3.

As described above, in the free casting apparatus according to the first exemplary embodiment, since the shape defining member 102 covers roughly the entire surface of the held molten metal M2, an undulation on the surface of the held molten metal M2 caused by the cooling gas can be prevented (or reduced). As a result, the size accuracy and the surface quality of the cast-metal article can be improved. In addition, it is possible to increase the casting speed and improve the productivity compared to the related art by increasing the flow rate of the cooling gas.

Further, the shape defining member 102 includes the refrigerant channel 2 a as cooling means for cooling the molten metal that is located near the outlet of the molten-metal passage section 103 and is passing through the shape defining member 102. Therefore, the shape defining member 102 can effectively cool the held molten metal M2 that has passed through the shape defining member 102, and thereby maintain the position of the solidification interface SIF in the vicinity of the shape defining member 102.

Further, the shape defining member 102 includes the heat-insulating film 2 b as temperature-maintaining means for maintaining the temperature of the molten metal M1 that is located near the inlet of the molten-metal passage section 103 and is going to pass through the shape defining member 102. Therefore, it is possible to prevent (or reduce) a decrease in the temperature of the molten metal M1 caused by the shape defining member 102 and improve the size accuracy and the surface quality of the cast-metal article.

Modified Example of First Exemplary Embodiment

Next, a free casting apparatus according to a modified example of the first exemplary embodiment is explained with reference to FIGS. 4 and 5. FIG. 4 is a plan view of a shape defining member 102 according to the modified example of the first exemplary embodiment. FIG. 5 is a side view of the shape defining member 102 according to the modified example of the first exemplary embodiment. Note that the xyz-coordinate systems shown in FIGS. 4 and 5 correspond to that shown in FIG. 1.

The shape defining member 102 according to the first exemplary embodiment shown in FIG. 2 is composed of one plate. Therefore, the thickness t1 and the width w1 of the molten-metal passage section 103 are fixed. In contrast to this, the shape defining member 102 according to the modified example of the first exemplary embodiment includes four rectangular shape defining plates 102 a, 102 b, 102 c and 102 d as shown in FIG. 4. That is, the shape defining member 102 according to the modified example of the first exemplary embodiment is divided into a plurality of sections. With this configuration, it is possible to change the thickness t1 and the width w1 of the molten-metal passage section 103. Further, the four rectangular shape defining plates 102 a, 102 b, 102 c and 102 d can be moved in unison in the z-axis direction.

As shown in FIG. 4, the shape defining plates 102 a and 102 b are arranged to be opposed to each other in the x-axis direction. Further, as shown in FIG. 5, the shape defining plates 102 a and 102 b are disposed at the same height in the z-axis direction. The gap between the shape defining plates 102 a and 102 b defines the width w1 of the molten-metal passage section 103. Further, since each of the shape defining plates 102 a and 102 b can be independently moved in the x-axis direction, the width w1 can be changed. Note that, as shown in FIGS. 4 and 5, a laser displacement gauge S1 and a laser reflector plate S2 may be provided on the shape defining plates 102 a and 102 b, respectively, in order to measure the width w1 of the molten-metal passage section 103.

Further, as shown in FIG. 4, the shape defining plates 102 c and 102 d are arranged to be opposed to each other in the y-axis direction. Further, the shape defining plates 102 c and 102 c are disposed at the same height in the z-axis direction. The gap between the shape defining plates 102 c and 102 d defines the thickness t1 of the molten-metal passage section 103. Further, since each of the shape defining plates 102 c and 102 d can be independently moved in the y-axis direction, the thickness t1 can be changed.

The shape defining plates 102 a and 102 b are disposed in such a manner that they are in contact with the top sides of the shape defining plates 102 c and 102 d.

Next, a driving mechanism for the shape defining plate 102 a is explained with reference to FIGS. 4 and 5. As shown in FIGS. 4 and 5, the driving mechanism for the shape defining plate 102 a includes slide tables T1 and T2, linear guides G11, G12, G21 and G22, actuators A1 and A2, and rods R1 and R2. Note that although each of the shape defining plates 102 b, 102 c and 102 d also includes its driving mechanism as in the case of the shape defining plate 102 a, the illustration of them is omitted in FIGS. 4 and 5.

As shown in FIGS. 4 and 5, the shape defining plate 102 a is placed and fixed on the slide table T1, which can be slid in the x-axis direction. The slide table T1 is slidably placed on a pair of linear guides G11 and G12 extending in parallel with the x-axis direction. Further, the slide table T1 is connected to the rod R1 extending from the actuator A1 in the x-axis direction. With the above-described configuration, the shape defining plate 102 a can be slid in the x-axis direction.

Further, as shown in FIGS. 4 and 5, the linear guides G11 and G12 and the actuator A1 are placed and fixed on the slide table T2, which can be slid in the z-axis direction. The slide table T2 is slidably placed on a pair of linear guides G21 and G22 extending in parallel with the z-axis direction. Further, the slide table T2 is connected to the rod R2 extending from the actuator A2 in the z-axis direction. The linear guides G21 and G22 and the actuator A2 are fixed on a horizontal floor surface or a horizontal pedestal (not shown). With the above-described configuration, the shape defining plate 102 a can be slid in the z-axis direction. Note that examples of the actuators A1 and A2 include a hydraulic cylinder, an air cylinder, and a motor.

Second Exemplary Embodiment

Next, a free casting apparatus according to a second exemplary embodiment is explained with reference to FIG. 6. FIG. 6 is a schematic cross section of a free casting apparatus according to the second exemplary embodiment. Note that the xyz-coordinate system shown in FIG. 6 also corresponds to that shown in FIG. 1. In the free casting apparatus according to the first exemplary embodiment, the shape defining member 102 includes the heat-insulating film 2 b on its underside as the temperature-maintaining means. In contrast to this, in the free casting apparatus according to the second exemplary embodiment, a shape defining member 202 includes a heater 22 b disposed in its lower part as the temperature-maintaining means.

Specifically, the shape defining member 202 includes the heater 22 b as the temperature-maintaining means for maintaining the temperature of the molten metal M1 located near the inlet of the molten-metal passage section 103. Therefore, it is possible to prevent (or reduce) a decrease in the temperature of the molten metal M1 caused by the shape defining member 202 and improve the size accuracy and the surface quality of the cast-metal article. The heater 22 b is formed, for example, in a ring shape so as to surround the molten-metal passage section 103.

Further, similarly to the shape defining member 102 according to the first exemplary embodiment, the shape defining member 102 according to the second exemplary embodiment covers roughly the entire surface of the held molten metal M2. Therefore, the shape defining member 202 can prevent (or reduce) an undulation on the surface of the held molten metal M2 caused by the cooling gas. As a result, the size accuracy and the surface quality of the cast-metal article can be improved. In addition, it is possible to increase the casting speed and improve the productivity compared to the related art by increasing the flow rate of the cooling gas.

Further, similarly to the shape defining member 102 according to the first exemplary embodiment, the shape defining member 202 according to the second exemplary embodiment includes a refrigerant channel(s) 2 a near the upper side (outlet side) of the molten-metal passage section 103 as the cooling means. Therefore, the shape defining member 202 can effectively cool the held molten metal M2 that has passed through the shape defining member 202, and thereby maintain the position of the solidification interface SIF in the vicinity of the shape defining member 202. Other configurations are similar to those in the first exemplary embodiment, and therefore their explanations are omitted.

Third Exemplary Embodiment

Next, a free casting apparatus according to a third exemplary embodiment is explained with reference to FIG. 7. FIG. 7 is a schematic cross section of a free casting apparatus according to the third exemplary embodiment. Note that the xyz-coordinate system shown in FIG. 7 also corresponds to that shown in FIG. 1. In the free casting apparatus according to the third exemplary embodiment, a shape defining member 302 includes an upper-part shape defining member 21 disposed on the upper side and a lower-part shape defining member 22 disposed on the lower side. In other words, the shape defining member 302 is divided, in the up/down direction, into the upper-part shape defining member 21 and the lower-part shape defining member 22.

The shape defining member 102 according to the first exemplary embodiment includes the heat-insulating film 2 b on its underside as temperature-maintaining means. In the shape defining member 302 according to the third exemplary embodiment, the lower-part shape defining member 22, which is in contact with the molten metal M1, is separated from the upper-part shape defining member 21 and hence thermally insulated from the upper-part shape defining member 21. Therefore, even when the lower-part shape defining member 22 includes no temperature-maintaining means, the decrease in the temperature of the molten metal M1 is reduced, thus making it possible to improve the size accuracy and the surface quality of the cast-metal article. Note that needless to say, the lower-part shape defining member 22 may include temperature-maintaining means such as the heat-insulating film 2 b according to the first exemplary embodiment and the heater 22 b according to the second exemplary embodiment.

Since the upper-part shape defining member 21 covers roughly the entire surface of the held molten metal M2, the upper-part shape defining member 21 can prevent (or reduce) an undulation on the surface of the held molten metal M2 caused by the cooling gas. As a result, the size accuracy and the surface quality of the cast-metal article can be improved. In addition, it is possible to increase the casting speed and improve the productivity compared to the related art by increasing the flow rate of the cooling gas.

Further, similarly to the shape defining member 102 according to the first exemplary embodiment, the upper-part shape defining member 21 includes a refrigerant channel(s) 2 a near the molten-metal passage section 103 as the cooling means. Therefore, the upper-part shape defining member 21 can effectively cool the held molten metal M2 that has passed through the shape defining member 302, and thereby maintain the position of the solidification interface SIF in the vicinity of the shape defining member 302. Other configurations are similar to those in the first exemplary embodiment, and therefore their explanations are omitted.

Note that the present invention is not limited to the above-described exemplary embodiments, and various modifications can be made without departing the spirit and scope of the present invention.

REFERENCE SIGNS LIST

2 a REFRIGERANT CHANNEL

2 b HEAT-INSULATING FILM

21 UPPER-PART SHAPE DEFINING MEMBER

22 LOWER-PART SHAPE DEFINING MEMBER

22 b HEATER

101 MOLTEN METAL HOLDING FURNACE

102, 202, 302 SHAPE DEFINING MEMBER

102 a-102 d SHAPE DEFINING PLATE

103 MOLTEN-METAL PASSAGE SECTION

104 SUPPORT ROD

105 ACTUATOR

106 COOLING GAS NOZZLE

108 PULLING-UP MACHINE

A1, A2 ACTUATOR

G11, G12, G21, G22 LINEAR GUIDE

M1 MOLTEN METAL

M2 HELD MOLTEN METAL

M3 CAST METAL

R1, R2 ROD

S1 LASER DISPLACEMENT GAUGE

S2 LASER REFLECTOR PLATE

SIF SOLIDIFICATION INTERFACE

ST STARTER

T1, T2 SLIDE TABLE 

1. A pulling-up-type continuous casting apparatus comprising: a holding furnace that holds molten metal; a shape defining member disposed near a molten-metal surface of the molten metal held in the holding furnace, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast by a molten-metal passage section through which the molten metal passes; and a nozzle that blows a cooling gas on the cast-metal article, the cast-metal article being formed as the molten metal that has passed through the molten-metal passage section solidifies, wherein the shape defining member comprises: cooling means for cooling the molten metal on an outlet side of the molten-metal passage section; and temperature-maintaining means for maintaining a temperature of the molten metal on an inlet side of the molten-metal passage section, and an end face shape of the molten-metal passage section is curved to conform to a surface shape of the molten metal pulled up from the molten-metal surface.
 2. The pulling-up-type continuous casting apparatus according to claim 1, wherein the temperature-maintaining means comprises a heat-insulating film formed on an undersurface of the shape defining means.
 3. The pulling-up-type continuous casting apparatus according to claim 1, wherein the temperature-maintaining means comprises a heater formed on the inlet side of the molten-metal passage section.
 4. A pulling-up-type continuous casting apparatus comprising: a holding furnace that holds molten metal; a shape defining member disposed near a molten-metal surface of the molten metal held in the holding furnace, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast as the molten metal passes through the shape defining member; and a nozzle that blows a cooling gas on the cast-metal article, the cast-metal article being formed as the molten metal that has passed through the shape defining member solidifies, wherein the shape defining member comprises: a lower-part shape defining member in contact with the molten metal held in the holding furnace; and an upper-part shape defining member disposed above the lower-part shape defining member, the upper-part shape defining member comprising cooling means for cooling the molten metal that passes through the upper-part shape defining member.
 5. The pulling-up-type continuous casting apparatus according to claim 1, wherein the cooling means is a channel through which a refrigerant flows.
 6. The pulling-up-type continuous casting apparatus according to claim 5, wherein the refrigerant is a gas.
 7. The pulling-up-type continuous casting apparatus according to claim 6, wherein the refrigerant is the same gas as the cooling gas.
 8. A pulling-up-type continuous casting method comprising: a step of pulling up molten metal held in a holding furnace while making the molten metal pass through a molten-metal passage section of a shape defining member, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast; and a step of blowing a cooling gas on the cast-metal article, the cast-metal article being formed from the molten metal that has passed through the molten-metal passage section, wherein the shape defining member comprises: cooling means for cooling the molten metal on an outlet side of the molten-metal passage section; and temperature-maintaining means for maintaining a temperature of the molten metal on an inlet side of the molten-metal passage section, and an end face shape of the molten-metal passage section is curved to conform to a surface shape of the molten metal pulled up from the molten-metal surface.
 9. The pulling-up-type continuous casting method according to claim 8, wherein a heat-insulating film formed on an undersurface of the shape defining means is used as the temperature-maintaining means.
 10. The pulling-up-type continuous casting method according to claim 8, wherein a heater formed on the inlet side of the molten-metal passage section is used as the temperature-maintaining means.
 11. A pulling-up-type continuous casting method comprising: a step of pulling up molten metal held in a holding furnace while making the molten metal pass through a shape defining member, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast; and a step of blowing a cooling gas on the cast-metal article, the cast-metal article being formed from the molten metal that has passed through the shape defining member, wherein the shape defining member comprises: a lower-part shape defining member in contact with the molten metal held in the holding furnace; and an upper-part shape defining member disposed above the lower-part shape defining member, and the upper-part shape defining member comprises cooling means for cooling the molten metal that passes through the upper-part shape defining member.
 12. The pulling-up-type continuous casting method according to claim 8, wherein a channel through which a refrigerant flows is used as the cooling means.
 13. The pulling-up-type continuous casting method according to claim 12, wherein a gas is used as the refrigerant.
 14. The pulling-up-type continuous casting method according to claim 13, wherein the same gas as the cooling gas is used as the refrigerant. 